title: Neonatal self-inflating bags: achieving titrated oxygen delivery using low flows: an experimental study.
abstract: OBJECTIVE
  To determine delivered O2 concentration (dFiO2) during manual inflations using neonatal self-inflating resuscitation bags (SIBs) at oxygen (O2) flow rates <1 L/min.
  
  
  METHODS
  This experimental study, determined dFiO2 during 216 sets of manual inflations at different O2 flow rate (L/min; 0.2, 0.4, 0.6, 0.8, 1.0 and 5.0), controlling peak inspiratory pressures (PIP; cm of H2O; 10-15, 15-20 and 20-25), inflation rates (per min; 30, 40 and 60), with and without O2 reservoir using two SIBs--the Laerdal infant resuscitator (240 mL) and Ambu Mark IV resuscitator (300 mL). A leak proof circuit connecting the SIB in series with pressure transducer, O2 analyzer and test lung was used. All possible combinations were tested four times each. The dFiO2 with each possible combination was compared using generalised estimating equation.
  
  
  RESULTS
  The mean dFiO2 with SIB even without reservoirs varied with rates and PIP from 75 to 93% at O2 flow rate of 5 L/min. At 1 L/min flow itself, 65-85% O2 is delivered. The dFiO2 was reduced to approximately 40% with flow of 0.2 L/min, PIP 20-25 cmH2O and inflations 40-60 per min.
  
  
  CONCLUSIONS
  During manual breaths using neonatal SIBs, the delivered O2 concentration of nearly 40% is attained at clinically used inflation pressures and rates by using lower flows. A graded increase in O2 delivery from 40 to 99% was obtained with flow varying from 0.2 to 5 L/min and addition of reservoir. However, even at such low flows, reduction in O2 concentration below 40% was unattained.
authors.affiliation: Division of Neonatology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Arun
authors.initials: A
authors.lastname: Sasi
authors.forename: Natarajan
authors.initials: N
authors.lastname: Chandrakumar
authors.forename: Ashok
authors.initials: A
authors.lastname: Deorari
authors.forename: Vinod K
authors.initials: VK
authors.lastname: Paul
authors.forename: Jeeva
authors.initials: J
authors.lastname: Shankar
authors.forename: Vishnubhatla
authors.initials: V
authors.lastname: Sreenivas
authors.forename: Ramesh
authors.initials: R
authors.lastname: Agarwal
mesh_terms: D004867:Equipment Design; D006801:Humans; D007231:Infant, Newborn; D010100:Oxygen / Q000008:administration & dosage*; D012121:Respiration, Artificial / Q000295:instrumentation*
chemical_list: D010100:Oxygen
keywords: FiO2; low flow; neonatal self-inflating bag; neonatology